High-humidity conditions (85−100% relative humidity (RH)) have very diverse effects on many aspects of people's daily lives. Despite remarkable progress in the development of structural coloration-based humidity sensors, how to significantly improve the sensitivity and visual humidity resolution of these humidity sensors under a high-humidity environment remains a great challenge. In this study, high-performance colorimetric humidity sensors based on environment-friendly konjac glucomannan (KGM) via thin-film interference are developed using a simple, affordable, and scalable preparation method. An effective strategy is demonstrated for substantially improving the sensor sensitivity and visual humidity resolution under a high-humidity environment via synergistic integration of multiorder interference peaks, sensor array technology, and superior water-absorbing polymer. The KGM full-range humidity sensors exhibit fast and dynamic response toward the humidity change without power consumption, and they also show high sensitivity and selectivity, little hysteresis, and excellent stability against high-humidity conditions. The KGM humidity sensors display extraordinary red shift of the reflection peak (e.g., 385 nm) and the visual humidity resolution as high as 1.5% RH in the visible range from 85 to 100% RH, which represent the largest spectra shift and highest visual humidity resolution, respectively, for structural coloration-based humidity sensors in high-humidity conditions.

In this work, the effects of changing molecular weight of polyol (2000, 3000, and 4000) and block ratio as well as deformation amplitude on thermal, structural, and shape memory properties of polyester urethanes based on diphenylmethane diisocyanate, polycaprolactone diol, and 1,4-butanediol were investigated. Fourier transform infrared spectroscopy was used to check the accomplishment of the polyurethanes synthesis. Thermal, structural, and shape memory properties of synthesized SMPUs were measured using differential scanning calorimetry, wide angle X-ray diffraction, and tensile cyclic tests, respectively. It was found that as the crystallinity of soft segments increased, the ability of the samples in fixation of temporary shape was higher. On the other hand, the shape recovery was dominated by the hard segment content and there was a minimum critical HSC for the samples to show appropriate shape memory effects.

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Pressure-assisted coating (PAC) is introduced to coat 3D-printed polymeric scaffolds with β-tricalcium phosphate (β-TCP) for tissue engineering applications. The method consists of four steps: infiltration of ceramic particles into the porous structure of the polymeric scaffold, dehydration of the slurry, compaction of ceramic particles around the scaffold, and heat treatment. The optimal coating is obtained at an infiltration speed of 400 mm/min followed by complete dehydration, compaction under ca. 8 MPa pressure, and subsequent heat treatment at 65 °C. The outcome is a uniformly coated scaffold with no deformation or structural defects, as confirmed by micro-CT analysis and laser and scanning electron microscopy. Scaffolds coated using the PAC method present superior interface bonding strength compared to those coated with a biomimetic approach. The contact angle decreased from 75.2 ± 1.4° for the uncoated scaffold to 39.6 ± 9.6° for the PAC specimen. PAC also increased the surface roughness from 0.66 ± 0.08 to 6.89 ± 0.26 μm and doubled the number of attached cells on the 3rd day of culture. The described method is applicable to different structures, object sizes, pore sizes, and shapes. For instance, in-depth coating of a 10 mm × 10 mm (D × H) cone with a 58 ± 4 μm-thick layer of β-TCP can be achieved using PAC. The method can be used to coat other polymers, such as poly­(lactic-co-glycolic acid) (PLGA). Successful coating of β-TCP on 3D-printed PLGA scaffolds is also presented as a proof of concept.